Tracer



Juy 9,A 193.. .J1 c. SHAW ET AL TRACR 2 sheets-sheet :e

Filed Jan. 5, 195:5

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INVENTORS 4 J. C. SHAW i SHAW ATTORN Y Patented July 16, 1935 c UNITEDSTATES PATENT OFFICE 'maciza John C. Shaw and Robert D. Shaw, Hartford,Conn., assignors to Pratt & Whitney Company, Hartford, Conn., acorporation of New Jersey Application January 5, 1933, Serial No.650,360

12 Claims. (Cl. 90-62) This improvement relates to acombination Afurther object of the invention is to produce contouring and depthgoverning tracer and more an attachment to, or suitable means forconvertparticularly to means for converting the well ing astandardcontourlng tracer into a combinaknown Keller contouring tracer into acombination tracer adapted for emcient, simultaneous,

5 tion tracer adapted to govern the depth of cut or three-dimensionaland contouring operations. 5 the in and out position of the tracer as itfollows This object may be accomplished by reversing the the contour ofa prole pattern on a curved surball and socket so as to provide for bothuniversal face. oscillatory or wobbling and longitudinal move- Diesinking machines of the Keller type, based ments thereof. In addition tothe contouring on Shaw Patent No. 1,506,454 and now well known tracercontacts, the opening and closing of which 10 in the trade, may be usedwith either a contourare controlled by the wobbling or oscillatory ingtracer or with the standard automatic threemovements of the tracer bar,there are added dimensional tracer substantially as described in frontand back depth governing contacts, substan- Shaw Patent No. 1,683,581 ofSeptember 4, 1928. tially the same as the front and back contacts of Thelatter patent, which shows and describes both the three-dimensionalstandard tracer. These forms of tracers, describes (page 11, lines 88 toare adapted to be opened and closed by longi- 98) how the contouringtracer may be used for tudinal movements ofthe tracer bar only toconthree-dimensional work, but in the operation detrol the in and outpositions of the tracer and scribed, the control of the depth or thirddimencutter.

sion is entirely manual and the operation becomes In the standardautomatic three-dimensional 20 a succession of proling cuts ofstep-by-step fortracer either wobbling or longitudinal movement mationat successively increased depth. of the tracer bar effects opening andclosing of The, Keller standard form of tracer for threethe front andback contacts mounted on the condimensional work, which is shown anddescribed tact carrying lever; LIn Athe present instance,

in' the above mentioned Shaw Patent No. 1,683, however, the Wobblingmovements of the tracer 25 581, while controlling the operation of themaare notutilized for this purpose, but only, as in chine from a,three-dimensional pattern in cutthe contouring tracer. for opening andclosing the ting various forms of dies, is .not particularly contourinetracer contacts. The Wobblins moveadapted for profiling work, such workbeing more ments of the tracer are rendered ineifective to eflicientlydone by the contouring'tracer. operate the front and back contacts byproviding 30 The contouring tracer is not, however, adapted vthe traceroperated arm of the ,Contact carrying for, nor is it capable ofautomatically controlling level With a Substantially lot Surface 01builion the depth of cut as the tracer follows the contour forcooperation with the rounded end of a nser of a profile template orpattern. When reproextension, axially of the usual contourng tracerducing the contour of a profile pattern, where the bar. This arrangementpermits the usual Wob- 35 prole represents a bead or similar outstandingbling movements 0f the tracer bar for` eieoting device on a curvedsurface, or where it is desired Contouling operations. but thesemovements Will to vary the depth of cut around the proie, the notoperate the Contact carrying lever to open standard type ofthree-dimensional tracer could and close the front and back contacts,the latter,

be used, but While capable of reproducing most aS previously explained.being opened and closed 40 any kind of work from a suitable pattern, inproonly by longitudinal movements of the tracer bar nie work it wouldrequire more time and be less to control respectively the in and out ordepth eicient than a contouring tracer, and the latter. governingmovements 0f the tracer. will reproduce any prole more accurately, with-One -form of this novel combination contouring out leaving feed lines orllets. and depth governing tracer is shown in the accom- 45 One object,therefore, of the present invention Danying drawings in Wllloll Fg- 1 iSa longitudinal is to produce a combination contouring and depth Section;Fig- 2 iS on end View looking from the governing tracer embodying allthe advantages of left end of Fig. 1; Fig 3 iS a Small sectional dethecontouring tracer for speed and accuracy of tail on lthe line 3--3 0fFig- 2; Figs. 4, 5, 6 and 7 to reproduction of a profile, vwithautomatic conare diagrams of pattern and tracer illustrating trol of thedepth of cut. That is, the in and out the operation of the 'tracer endFg- 3 iS a Wiring position ofthe cutter is automatically determineddiagram 'of circuits for ille tracer. relays and so that profiles ofirregular depth, or proles magnetic clutches.' formed upon irregular orcurved surfaces may be The present improvement, therefore, providesautomatically reproduced. a body portion l, in which a tracer bar 2,carrying CII the tracer point 3, is mounted for both wobbling oruniversal lateral movements and for longitudinal movements. In, thecontouring tracer shown in Patent No. 1,683,581, the tracer bar issupported in the body portion by a hemispherical socket bearing, theopen end of which is outward or toward the model contacting end of thetracer bar, so that backward longitudinal movement of the tracer barfrom its'seat is not permitted. In order to provide for longitudinalmovements as well as the wobbling or lateral movements, the tracer bar2, in the present instance, is provided with a substantiallyhemispherical collar 4 held in place by a screw-threaded nut 5 andsupported in a hemispherical socket bearing 6, the larger open end ofwhich is inward or away from the tracer point 3. In,y addition, thesocket 8 is provided with a cylindrical portion at 1 tting a recessformed in the body member I. This bearing socket 6 is held in place bythe usual screw threaded thimble 8, which may be locked in place by thescrew 9. The opposite or head end of the body portion I is provided withan enlarged section II), preferably mounted on the bearing section bybeing screw-threaded at II and held in proper register therewith by aset screw I2.

A counterbalancing device is shown at I3 in the form of a springnormally forced against the bar 2.

The enlarged end IIJ of the body portion is preferably provided with apartition I4, having a central opening through which the reduced end I5of the tracer bar passes, as shownin Fig. 1. The

end I5 of the tracer bar is provided with a collar I8 supporting anannular contact carrying member I1, provided with four contactsl I8, 90apart and arranged to cooperate with four circumferentially' arranged,inwardly projecting fixed contacts I9 mounted in the front part of thebody section I and equally spaced circumferentiallyof the tracer bar.

The fixed contacts I8 are mounted on adjusting screws 28, which aresupported by suitable insulated bushings 2|, the respective contactshaving wiring connections to the usual magnetic clutches for controllingthe two contouring motions, substantially asshown in the wiring diagramof Fig. 8, and described in the hereinbefore mentioned patents.

The magnetic clutch circuits for the respective contouring tracer feedsare closed by closing one or the other of the four contacts I8 on thetracer bar, with the corresponding contact I9 on the body portion andthese contacts, as previously explained, are closed only by wobbling orlaterial movements of the tracer bar 2, as the tracer follows thecontour or peripheral edge of a profile pattern.

A spring 22, or other suitable resilient member, is connected withtheinner end of the tracer bar at 23; the opposite end of the springbeing connected at 24 with a rotatable selector ring 25 for selectingthe contacts to be normally resiliently closed. In the present instance,the ring 25 is provided with bevel gear teeth 26 meshing with 'the teethof a bevel pinion 21 supported in an annular guard ring 28 secured bysuitable screws 29 to the body section I8. The guard ring 28 is providedwith an inwardly projecting annular flange 30 which serves as a bearingsupport for the rotatable selector ring 25 and holds it in place.

Obviously, the selector ring 25, supporting the outer end of theradially arranged spring 22, may be rotated in any suitable manner, butfor the larger machines, it is preferable to provide the gear and piniondrive, 28 and 21, and connect the pinion 2B with a flexible shaft andhandle member for distant lcontrol. Accordingly, the pinion shaft 3| ismounted in a bearing collar 32 secured to the guard ring 28 in anysuitable manner. As indicated in Fig. l, the outer end 34 of the pinionshaft is connected by a suitable universal joint 35 with1 aninterconnecting telescoping shaft 36, the latter being connected througha universal joint 31 with the shaft 38 of a bevel pinion 39, meshingwith a bevel gear 40, mounted on a shaft 4I, rotatably supported inaframe 42.

The outer end of the shaft 4I is provided with the usual pointer handle43, for rotating the gear 40, and, through shaft 3G and pinion 21, theselector ring 25 and resilient member 22, the position of which may bereadily determined by suitable indices 44 arranged in opposite quadrantson the face of the supporting frame 42.

Also in the present instance the bearing socket 4-8 has been reversedand arranged to permit backward movement of the tracer bar from theposition shown so as to provide for operating the depth governingcontacts.

While the combination tracer is here shown as a complete instrument, itwill be understood that the depth governing feature may be consideredsubstantially as an attachment for the standard contouring tracer. Tomake this conversion, the reduced end I of the contouring tracer bar 2is extended axially by means of a round ended4 iinger 45, screw threadedat 46 and screwed into the end of the tracer bar in place of the screwwhich ordinarily is provided for holding the link 23 for supporting theinner end of the spring 22. In order to support the depth governingcircuit controlling contacts in position for operation by longitudinalmovement of the tracer iinger, a frame 41, having an outer plate 48, issecured by suitable screws 49 to the contouring tracer guard ring 28which, as described, is mounted on the end of the body section I0,substantially as shown in Fig. 1.

'I'he supporting plate 48 for the depth governing. portion of thecombination tracer corresponds substantially with the front plate oftheautomatic three-dimensional electric tracer as shown and described inShaw Patent No. 1,683,581. In the present instance, a yoke bracket 50 issecured by suitable screws 5I tothe frame plate 48 and this bracket isprovided with pivot supporting screws 52 cooperating with a lever pivot53 in supporting the contact carrying lever 54.

The contact carrying lever 54 is, in the form here shown, provided witha leaf spring resilient member 55 carrying at its upper end both a frontcontact 56 and a back contact 51. The front contact 56 is arranged tocooperate with a fixed contact 58 on the end of an adjusting screw 59,suitably supported in an insulating bushing in the plate 48. The contactcarrying screw 59 is preferably connected by a strip 60 (Fig. 2) with abinding screw terminal 5 I, to which the magnetic clutch relay circuitis connected for controlling the in motion of the tracer and cutter ashereinl front plate 48 by a screw 65 which, by means of a thumb nut 68,serves as a binding screw terminal-to which the relay circuit of the outmagnetic clutch is secured as hereinafter described (see Fig. 8). Thebracket 64 and screw 65 are suitably insulated from the plate 48.

Preferably a tension spring $1 and compression spring 68 cooperate toactuate the contact carrying lever 54 and to normally maintain the frontcontacts 56, 58 in closed circuit. Suitable adjusting screws and nuts 89and 10 are provided for adjusting the tension of the respective springs81 and 68. The tracer, including the tracer bar and tracer body, isgrounded to complete the circuit, as indicated in Fig. 8.

'I'he movements of the contact carrying lever 54 are controlled bylongitudinal movements of the tracer bar 2, the arrangement being suchthat the linger 45 on the end of the tracer bar engages the short arm ofthe lever which is preferably provided with a hardened button or block1| mounted upon or inserted in the contact carrying lever 54 below thepivot 53. By this arrangement it will be seen that the action of thesprings 61 and 68 is to thrust the button 1| against the end of theiinger 45, thereby holding the hemispherical bearing member 4 in itssocket 6 and at the same time holding the front contacts 51-58 closed,except'when the tracer bar is displaced longitudinally by pressure onthe end of the tracer 3.

In the standard three-dimensional tracer (Patent No. 1,683,581) thecontact carrying lever, corresponding to the lever 54, is provided witha conical socket member cooperating with the end of the tracer bar sothat both wobbling and longitudinal movement of the latter will operatethe contact lever. In the present instance, however, the conical socketis replaced by the flat faced button 1| or one having a concavespherical surface of large radius. By this connection wobbling movementsof the tracer bar 2 will not move the contact carrying lever 54, andopening and closing of the front and back contacts is controlled only bylongitudinal movements of the tracer bar. Obviously, since the tracerbar 2 wobbles about in the socket bearing 4 -6 as a fulcrum, the surfaceof the button 1| should theoretically be spherical, withthe fulcrumpoint as the center, but the wobbling motion of the tracer bar is re1-atively so' small that for -practical purposes, the surface of thebutton 1| may be substantially at.

In the wiring diagram of Fig. 8, the contouring contacts and operatingportions of the com bination tracer are given the correspondingpreviously used reference numbers and for clearness the tracer bar anddepth governing portion are shown separately but, as will be understood,the circuits are all operated from the same source. Thecircumferentially arranged contouring contacts |9 on the body portion l0are preferably designated N, S, E and W, representing the cardinalpoints which are used to designate the directions of the motions. Thedesignations areoppositely placed around the tracer head because Northmovement of the tracer 3 means downward movement of the other end l5 ofthe tracer bar 2.

The North and South contact screws 20 are connected by lowvoltagecontrol' circuits 12 and 18 with relay magnets 14 and 15, designatedrespectively N and S. The E and W contact screws 20 are similarlyconnected by low voltagecontrol circuit leads 18 and 11 with relaymagnets 18 and 19 designated respectivcly`E and W. The circuits of therespective relay magnets 10 and 15 are completed through leads and 8| tolead 82, which in turn is connected with lead 83, connected with oneterminal of thelfl volt generator 84 for the control circuits, the otherside of the circuit being connected to ground by lead 85.

It has been previously pointed out that the tracer bar 2|5 is groundedas indicated at 86 so that the respective relay circuits are completedback to the generator 84.

The W and E relay magnets 18 and 19 are similarly connected to lead 83byleads 81, 88 and 89. The N and S magnets 14 and 15 are arranged toactuate a two-way swinging armature (normally centralized by springs)connected vin the higher voltage (110 volts) operating circuit by lead9|, which in turn is connected with lead 92, designated as the plus sideof the 110 volt circuit.V

Similarly the W and E magnets 18 and 19 are arranged to actuate atwo-way swinging armature 93 (normally centralized by springs) connectedby lead 94 with the lead 92 or plus side of the 110 volt circuit.

The N and S armature 90 is, therefore, adapted to close the highervoltage operating circuit through leads 95 or 96 to the respective`magnetic clutches 91 or 98, designated Nland S. These clutches, as willbe understood in the operation of the Keller machine tools, are adaptedfor eiecting the vertical or up and down motions of the tracer andcutter. 'I'he circuits of magnetic clutches 91 and 98 are completedthrough leads 99 and |00, to lead |0| representing the negative side ofthe volt circuit.

Similarly the armature 93 of the W and E rela'y magnets 18 and 19 isadapted to close a clutch operating circuit through the leads |02 or |03to the respective magnetic clutches. |04 or |05, designated as W and E,which in the operation of the Keller machine are for longitudinalmotions and move the tracer and cutter to the right (E) or to the left(W). The operating circuits for magnetic clutches |09 and- |05 arecompleted by leads |06 and 001 to the lead |0| representing the negativeside of the 110 volt circuit.

The rotatable resilient member or spring 22, which normally is adaptedto close the contouring tracer contacts I8 and I9, as previously pointedout, is adapted to close on only two contacts, on one side of the tracerbar, that is, on the side of and in the line of action of the spring.`In Fig. 8, the ring 25 is turned so that the spring 22 is in position toclose the contacts of circuits N and E, the S and W circuits being open.

Longitudinal movements of -the tracer bar 2 by engagement ofthe tracerwith the pattern, and the finger 45 pressing against the at surface 1|of the operating arm of the contact carrying lever 54, are adapted toopen and close the front and back contacts F16-58 and 51--62, for the inand out motions of the tracer and cutter, substantially as described inShaw Patbrought into operation only by closing the contouring tracercontacts N, S, E and W.

As previously pointedout, in. the depth governing attachment the springs61 and normally maintain the contacts 56-58 closed for in motion, thefixed contacts 58 being connected, in the low voltage or controlcircuit, by lead |08 to relay magnet |09 designated in. The

circuit from the in magnet |09'is completed by lead IIO to lead 83 andthence to the 14 volt generator 84, which as previously described, isgrounded at 85, thus completing the circuit to the tracer bar which isgrounded at 86.

The depth governing back contact 51-62 is adapted to close the tracergrounded circuit through lead III to relay magnet II2, designated out,the circuit being completed through lead II3 to lead 83 and back to the14 volt generator 84 and to ground 85 as previously described. A two-wayswinging armature I I4, centralized by springs and operating between therelay magnets I09 and H2 is connected by leadl l5 with lead 92, whichrepresents the positive of the clutch operating volt circuit.

According to this arrangement, actuation of the armature H4 by the in"relay magnet |09 closes the circuit through lead II6 to the magneticclutch I Il, designated in for in motion, the circuit being completedthrough lead IIB to lead IOI, representing the negative side of theclutch operating I I0 volt circuit.

Similarly, operation of the armature I I4 by the out relay magnet II2completes the circuit through lead H9 to magnetic clutch |20, designatedout, the circuit being completed through lead I2I to lead IOI,representing the negative side of the 110 volt circuit.

It will thus be seen that the in and out depth governing motions and theposition of the tracer and cutter for the depth of cut are controlled byoperation ofthe magnetic clutches II'I and |20 through the opening andclosing ofthe front and back tracer contacts 56-58 and 51-62 and theopening and closing of these contacts is controlled only by longitudinalmovements o-f the tracer bar 2. The finger 45 cooperating with the fiatsurface 1I permits the wobbling moveside `ments of the tracer bar to beusedsolely for controlling the opening and closing of the contouringtracer contacts I8, I9, for N, E, S and W motions, as previouslyexplained.

The operation of the combination tracer, merely as a contouring tracerfollowing the edge of a template of the usual form, will besubstantially the same as with the standard contouring' tracer. But whenthe profile to be reproduced varies in depth, or extends over a curvedor wavy surface the depth governing feature of the present improvementis vbrought into action to vary the position of the cutter as the tracerfollows a suitable curved or depth governing pattern, arranged forcooperation with the template or pattern representing the profile to berepro-` duced by the contouring tracer, or upon which a bead or profileis mounted.

The combination tracer is particularly adapted for the character of workshown in Figs. 4 and -5, where a curved form of pattern is shown with abead projecting therefrom. It will be noted that as the tracer 3 followsthe profile of the bead A, the point of the tracer will come in contactwith the curved surface B of the pattern and as a result of longitudinalmovements of the tracer bar 2 the contacts 50-58 and 57--62 controllingthe magnetic clutches will gradually Work the tool around the curve andform a bead of uniform depth on the curved surface. Simultaneouslyduring this operation the contouring tracer contacts I8 and I9 under theaction of spring 22 are being closed and opened according to thedirections of motions required, the directions being controlled by theposition of the spring 22. The position of the spring 22, as previouslypointed out. is controlled by the handle 43 in cooperation with theposition indicating indices 44 (Fig.4 1).

In the combination tracer as herein described, the wobbling movements ofthe tracer cannot control the in and out position of the cutter when theangle between the axis of the tracer point and the pattern is relativelygreat. For instance, as will be seen in Fig. 6, an excessive angle fromthe perpendicular will fail to produce the required longitudinalmovement of the tracer bar to operate the contact carrying lever 54, thetracer oscillating instead of moving backward. Hence, the form ofcombination tracer illustrated can be used only to follow a patternwhere the angle of the tracer to the surface is less than approximately45. If the angle is about 45 or more, the end pressure for axialmovement of the tracer bar will not be suicient to operate the contactcarrying lever 54 to open or close the contacts for the in and outmotions.

Fig. 7 indicates how the combination tracer can be used to follow adepth governing model and at the same time follow the outline of acontour 'template superimposed thereon, this arrangement being suitablefor the reproduction from the same outline of work pieces of differentthickness or with Walls of different depths.

`The combination tracer, therefore, combines in a single instrument boththe standard contouring tracer and the essential feature of theautomatic tracer, that is, control of the in and out motions forgoverning the position of the cutter, thereby, increasing both the speedand accuracy of reproduction and eliminating the necessity for accurateadjustments when work of this character is required to be reproduced.Such work can be done by using one or both types of standard tracers,but the trouble and accuracy of setting involved is likely to be'prohibitive.

It will be understood that the preferred form of the combination traceris here shown and described, but obviously, various changes in theAspecific construction and arrangement of the.

controls for the several circuits may be made without departing from thespirit and scope of the invention. v

What we claim is:

1. A combination contouring and proling tracer comprising incombination, a body mem-5 ber, a universally oscillatory andlongitudinally movable tracer bar therein, contacts opened and closed byoscillatory movements of said bar, and

contacts opened and closed by longitudinal movement of said bar, saidlatter contacts being opened and closed with the bar in any oscillatedposition.

2. A combination contouring and profiling tracer comprising incombination, a body member, a universally oscillatory and longitudinallymovable tracer bar therein, contacts opened and closed by oscillatorymovements o-f said bar in any longitudinal 'position of said bar, andcontacts opened and closed by longitudinal movement of said bar in anyoscillated position of said bar. y

3. A combination contouring and depth governing tracer comprising, atracer bar mounted for both oscillatory and longitudinal movements,contouring circuit closing contacts equally spaced circumferentially ofsaid tracer bar, the opening and closing of which is controlled by saidoscillating movements thereof, and depth governing circuit closingcontacts, the opening and closing of which is controlled by saidlongitudinal movements of the tracer bar.

movements of the tracer bar in any oscillated` position of said tracerbar.

l 5. A combination contouring and depth governing tracer comprising, atracer bar mounted for universal oscillatory and longitudinal movements,four circuit closing contacts equally spaced circumferentially of saidtracer bar, the opening and closing of which are controlled by saidlateral movements of said tracer bar as the tracer follows the contourof a pattern, and depth governing circuit closing contacts, the openingand closing of which is effected by longitudinal movements of the tracerbar as the tracer follows a depth governing pattern.

6. A combination contouring and depth governing tracer comprising, atracer bar mounted for universall lateral movement, circuit closingcontouring tracer contacts equally spaced circumferentially of saidtracer bar, Opposite circuit contacts being inl opposite quadrants, artatable resilient member arranged to move said tracer bar laterally forclosing contacts in adjacent quadrants, means for mounting said tracer`bar for longitudinal -movements axially, a contact carrying leverhaving front and back circuit closing contacts arranged to be openedandclosed by said longitudinal movements of the tracer bar, means forresiliently holding the tracer bar in such position axially that saidfront contact is normally closed, and engaging means between said leverand the tracer bar whereby opening and closing of said front and backcontacts may be effected in any oscillated position of said tracer bar.

7. A combination contouring 'and depth governing tracer comprising,a'tracer bar, contouring circuit closing contacts arrangedcircumferentially of sa'id tracer bar, opposite circuit cony tacts beingin opposite quadrants, 'magnetic clutches, the circuits of which areadapted to be opened and closed by said contouring contacts as thetracer follows a contour pattern, means for mounting said tracer bar forboth universal lateral and longitudinal movements, said contouringcontacts being arranged to be opened and closed by lateral movements ofthe.tracer bar, depth governing circuit closing contacts arranged to beopened and closed by longitudinal movements of said tracer bar, andmagnetic clutches for in and out motions, the circuits of which arecontrolled by the opening and closing of said depth governing contactsas the tracer follows a `depth governing pattern.

8. A combination contouring and depth governing tracer comprising a bodyportion, a tracer bar supported in said body portion for universallateral and longitudinal movements, four circuit terminal contactsdisposed about the tracer bar and mounted on said body portion andequally spaced circumferentially, four cooperating contacts carried bysaid tracer bar for closing the respective circuits of the terminalcontacts by lateral movements oflsaid tracer bar as the tracer followsthe contour outline, a rotatably supported resilient member connectedwith said tracer bar and rotatable thereabout for urging the closing of4two adjacent contacts according to the line o1' action of saidresilient member, an auxiliary frame for depth governing contactssecured to the end of said portion, circuit terminal contacts on saidframe and a lever having front and back contacts mounted for cooperationwith said frame contacts, said lever being fulcrumed on a pivottransversely of said tracer bar and provided with a'substantially flathardened surface cooperating with an axial extension on said tracer barfor rocking said lever for opening and closing said depth governingcontacts by longitudinal movements of the tracer bar.

9. A combination contouring and depth governing tracer comprising a bodyportion, a tracer bar carrying a tracer at its outer end, means formounting the tracer bar in said body portion for universal lateral andlongitudinal movements,

four terminal contacts for magnetic clutch circuits mounted on said bodyportion andequally spaced circumferentially of the tracer bar, fourcorresponding circuit closing contacts carried by the tracer bar forclosing the respective magnetic clutch circuits by lateral movements ofsaid tracer bar as the tracer follows the contour of a pattern, y

a contact carrying lever pivotally supported by said body portion formovement in the plane of said tracer bar, a finger at the inner end ofthe tracer bar engaging said lever for moving the latter by longitudinalmovements of the tracer bar as the tracer follows a depth governingpattern, terminal contacts on said frame for magnetic clutch circuitsfor in and out depth governing motions, circuit closing contacts on saidlever for cooperation with the contacts on said frame, and resilientmeans for maintaining the in contact normally closed and said lever incontact withv the tracer bar finger.

l0. A combination contouring and depth governing tracer comprising abody portion, a tracer bar mounted in said body portion for universallateral and longitudinal movements, four terminal contacts equallyspaced circumferentially of said tracer bar for controlling thecircuitsv of magnetic` clutches for contouring motions, four equallyspaced contacts carried by said tracer bar for engaging the first namedcontacts and closing the respective magnetic clutch circuits, arotatable radially acting resilient member connected with the tracer barfor urging the closing of said contacts in the direction of pull of saidresilient member, a contact carrying lever pivotally supported by saidYbody portion for movement in a plane at right angles to the plane ofsaid contouring contacts, front and back contacts on said lever,contacts for magnetic clutch circuits controlling in and out motionssupported by said body portion for cooperation with said front and backcontacts and cooperative means between said lever and the tracer barwhereby longitudinal movements of the latter are effective for openingand closing said lever contacts under the control of a depth governingpattern as the tracer follows the contour of a prole pattern.

ll. A depth governing attachment for contouring tracers wherein auniversally oscillatory tracer bar carries contacts cooperating withcontouring tracer contacts arranged circumferentially of the tracer bar,comprising means for mounting said tracer bar for longitudinal movementsin addition to said oscillating movements, a nger mounted on the end ofsaid contouring tracer bar, a contact carrying lever having a flatsurface cooperating with said finger, the cooperation being such thatoscillating movements of the tracer bar do not cause movement of saidlever, movements of the lever being effected only by longi-` tudinalmovements o f said tracer bar, and cooperating circuit closing contactsarranged to bev opened and closed by said lever by longitudinalmovements of the tracer bar.

12. A depth governing attachment for contouring tracer having a bodyportion supporting a tracer bar normally mounted in a hemisphericalsocket bearing permitting universal oscillatory aoovgeoo front and backcontacts pivotally supported in said frame for movement in the plane ofthe tracer bar, an operating arm on said lever provided with asubstantially at operating surface, a ringer secured to the end of thecontouring tracer bar and extending into said frame for cooperation withthe iiat surface of said arm, said flat surface permitting oscillatorymovements of the tracer bar without operating the lever to open andclose said lever contacts, said lever contacts being opened and closedonly by longitudinal movements of the tracer bar, and resilient meanscontrolling longitudinal movements of the tracer bar and the opening andclosing of said lever contacts.

' JOHN C. SHAW.

ROBERT D. SHAW.

